Threat Encyclopedia

RANSOM_CRYPTRITU.A

Publish date: January 05, 2016

ANALYSIS BY

David John Agni


PLATFORM:

Windows

OVERALL RISK RATING:
DAMAGE POTENTIAL:
DISTRIBUTION POTENTIAL:
INFORMATION EXPOSURE:

  • Threat Type:Trojan

  • Destructiveness:No

  • Encrypted:

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This is the Trend Micro detection for the latest variant of ransomware that is written in JavaScript. Based on reports, it has capabilities to run on Windows, Mac OS X and Linux.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.

TECHNICAL DETAILS

File Size:

23,530,786 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Feb 2016

Payload:

Connects to URLs/IPs, Compromises system security, Encrypts files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following files:

  • %Application Data%\Chrome Browser\chrome - copy of the GPL licensing agreement
  • %Application Data%\Chrome Browser\chrome.exe - NW.js package application contains the actual malicious routine.
  • %Application Data%\Chrome Browser\icudtd.dat - NW.js framework component
  • %Application Data%\Chrome Browser\ffmpegsumo.dll - NW.js framework component
  • %Application Data%\Chrome Browser\nw.pak - NW.js framework component
  • %Application Data%\Chrome Browser\g - config file (Bitcoin address, Error Message, Affiliate ransom amount)
  • %Application Data%\Chrome Browser\rundll32.exe - Renamed TOR client used for C2 communication
  • %Application Data%\Chrome Browser\msgbox.vbs - script used to display the Error Message
  • %Application Data%\Chrome Browser\s.exe - used to drop the shortcut file in %User Startup% folder
  • %Application Data%\Chrome Browser\u.vbs - Enumerates and deletes all files and folder in the specified directory.

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It creates the following folders:

  • %Application Data%\Chrome Browser

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • ChromeService.lnk - shortcut file that points to %Application Data%\Chrome Browser\chrome.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.40.189:443
  • http://{BLOCKED}.{BLOCKED}.244.244:443
  • http://{BLOCKED}.{BLOCKED}.105.57:9001
  • http://{BLOCKED}.{BLOCKED}.92.11:9101
  • http://{BLOCKED}.{BLOCKED}.93.36:9001
  • http://{BLOCKED}.{BLOCKED}.92.11:9001
  • http://{BLOCKED}.{BLOCKED}.18.110:80

It encrypts files with the following extensions:

  • *.jpg
  • *.jpeg
  • *.raw
  • *.tif
  • *.gif
  • *.png
  • *.bmp
  • *.3dm
  • *.max
  • *.accdb
  • *.db
  • *.dbf
  • *.mdb
  • *.pdb
  • *.sql
  • *.*sav*
  • *.*spv*
  • *.*grle*
  • *.*mlx*
  • *.*sv5*
  • *.*game*
  • *.*slot*
  • *.dwg
  • *.dxf
  • *.c
  • *.cpp
  • *.cs
  • *.h
  • *.php
  • *.asp
  • *.rb
  • *.java
  • *.jar
  • *.class
  • *.aaf
  • *.aep
  • *.aepx
  • *.plb
  • *.prel
  • *.prproj
  • *.aet
  • *.ppj
  • *.psd
  • *.indd
  • *.indl
  • *.indt
  • *.indb
  • *.inx
  • *.idml
  • *.pmd
  • *.xqx
  • *.xqx
  • *.ai
  • *.eps
  • *.ps
  • *.svg
  • *.swf
  • *.fla
  • *.as3
  • *.as
  • *.txt
  • *.doc
  • *.dot
  • *.docx
  • *.docm
  • *.dotx
  • *.dotm
  • *.docb
  • *.rtf
  • *.wpd
  • *.wps
  • *.msg
  • *.pdf
  • *.xls
  • *.xlt
  • *.xlm
  • *.xlsx
  • *.xlsm
  • *.xltx
  • *.xltm
  • *.xlsb
  • *.xla
  • *.xlam
  • *.xll
  • *.xlw
  • *.ppt
  • *.pot
  • *.pps
  • *.pptx
  • *.pptm
  • *.potx
  • *.potm
  • *.ppam
  • *.ppsx
  • *.ppsm
  • *.sldx
  • *.sldm
  • *.wav
  • *.mp3
  • *.aif
  • *.iff
  • *.m3u
  • *.m4u
  • *.mid
  • *.mpa
  • *.wma
  • *.ra
  • *.avi
  • *.mov
  • *.mp4
  • *.3gp
  • *.mpeg
  • *.3g2
  • *.asf
  • *.asx
  • *.flv
  • *.mpg
  • *.wmv
  • *.vob
  • *.m3u8
  • *.csv
  • *.efx
  • *.sdf
  • *.vcf
  • *.xml
  • *.ses
  • *.dat

NOTES:

It avoids encrypting files in the directories that contain the following strings:
:\windows\
:\winnt\
programdata\
boot\
temp\
tmp\
$recycle.bin\

It executes the following command:

  • to cscript msgbox.vbs 16 {ERROR MESSAGE}

Where {ERROR MESSAGE}depends on the config file.

After its encryption routine it displays the following Window containing ransom notes and information on how to recover the encrypted files.

SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.252.05

FIRST VSAPI PATTERN DATE:

04 Jan 2016

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
 
  • %Application Data%\Chrome Browser

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Startup%\ChromeService.lnk

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTRITU.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 7

Reset Internet security settings

[ Learn More ]

NOTES:
Restore the encrypted files from backup.


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